Habitat disturbance caused by wind energy facilities creates unique challenges and opportunities for wildlife. Although fragmented landscapes may make some large carnivores -- like cougars and bears -- more vulnerable to population decline, some small- to medium-sized animals -- like coyotes and foxes -- expand their habitat to include areas that have been changed by humans.

“These findings could be helpful in assisting managers to design future wind energy facilities with species in mind,” said lead author Mickey Agha, a UC Davis graduate student studying ecology with Professor Brian Todd. “There may be benefits to adding space between turbines and increasing the number of dirt roads, to potentially provide habitat for sensitive terrestrial wildlife.”

Results suggest that infrastructure associated with wind energy facilities, such as dirt roads or culverts, may create movement corridors through disturbed habitat that some animals prefer. Dirt roads may act as funnels for predators because they are potential corridors through the wind energy facility. Earlier research at the study site reported that tortoise burrows were more likely to be closer to roads than random points. Tortoises can move more easily on dirt roads and desert washes than on highly vegetated landscapes.

Burrow Visits May Be for Smaller Prey

“There is little information on predator–prey interactions in wind energy landscapes in North America, and this study provides a foundation for learning more,” said Jeffrey Lovich, USGS scientist and co-author of the study. “Further investigation of causes that underlie road and wind turbine effects, such as ground vibrations, sound emission and traffic volume could help provide a better understanding of wildlife responses to wind energy development.”

The cameras did not record any predation on adult desert tortoises close to burrows. This suggests that the predators observed in the study do not often actively prey upon adult desert tortoises, but visit the sites looking for smaller prey that frequently live in desert tortoise burrows.

The study was funded by California Desert Managers and the USGS Ecosystems Program.

This American black bear and cub duo was seen simply investigating a tortoise burrow, and although it is surprising to see a black bear so low in elevation, it isn't impossible. The study site, Mesa, sits at the intersection of multiple ecosystems (Sonoran Desert, Mojave Desert, montane, and coastal sage scrub). Therefore, the bears could have come down from the montane area.

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There were two documented gray fox visits at the burrows, making them the third most documented predator. Gray foxes are implicated predators of various life stages of desert tortoises, but it is difficult to catch them in the act. In this case, a gray fox approaches a burrow, and thoroughly investigates the burrow mouth. The fox develops an arch in its tail (slight inverted U-shape) indicative of an alert or hunting behavior. The tail subsequently drops its arch as the fox loses interest and walks away. Scientists presume there was no tortoise in the burrow at this time (the last time a tortoise was seen entering or exiting was a week prior). Although camera traps are a useful monitoring technique, they sometimes fail to yield a complete story - often scientists would see a tortoise enter a burrow, but never leave. This obviously wasn't the case, as during this time tortoises were radio-tracked and they did move about.

Infrastructure associated with wind energy facilities can influence the behavior of animal predators and their prey, according to a recent study by University of California – Davis and the USGS.

Motion-sensor cameras were placed facing the entrances of 46 active desert tortoise burrows in a wind energy facility near Palm Springs, California. Recordings showed that visits to burrows from four predators increased closer to dirt roads, and decreased closer to wind turbines.

There was one documented skunk event captured on camera - the least documented predator. Here, a western spotted skunk is thoroughly investigating the burrow of one of the marked female tortoises in the study population. Western spotted skunks are known predators of turtle eggs. The skunk investigated the area within the burrow for a full minute before it appears outside of the burrow looking alertly in one direction, then running off screen in the opposite direction. This event took place in October, which is a bit late for eggs to be in a nest, but the nesting season for tortoises at the study site ranges from 12 May to 8 July and hatchlings emerge from their nests from 7 August to 29 September, and this period overlaps broadly with the dates where predators were observed at tortoise burrows.

Infrastructure associated with wind energy facilities can influence the behavior of animal predators and their prey, according to a recent study by University of California – Davis and the USGS.

Motion-sensor cameras were placed facing the entrances of 46 active desert tortoise burrows in a wind energy facility near Palm Springs, California. Recordings showed that visits to burrows from four predators increased closer to dirt roads, and decreased closer to wind turbines.

In this video, a bobcat approached a desert tortoise (a marked female in the study population) that was sleeping on the apron of her burrow. Bobcats are known predators of various life stages of the desert tortoise. In this case, the bobcat bent down to sniff the tortoise, and then touched its paw to the top of the tortoise's shell. The tortoise then moved into an "all-defensive" position, where it tucks head and limbs into the shell. The bobcat apparently loses interest and walks away after this. Another interaction of a different bobcat and the same tortoise followed shortly after, but again no predation was observed. Lucky tortoise! Bobcats were the predator that was most often observed at burrows on our trail cameras.

Infrastructure associated with wind energy facilities can influence the behavior of animal predators and their prey, according to a recent study by University of California – Davis and the USGS.

Motion-sensor cameras were placed facing the entrances of 46 active desert tortoise burrows in a wind energy facility near Palm Springs, California. Recordings showed that visits to burrows from four predators increased closer to dirt roads, and decreased closer to wind turbines.

Coyotes were the second most frequently observed mammalian predator on the trail cameras. Coyotes are considered one of the primary predators of desert tortoises. In this instance, a coyote is passing by a burrow when it suddenly has a change in attention as it is passing by. It then approaches the burrow and sniffs all around the burrow entrance (including the apron and overhanging plants) before it decides to move on. Scientists mostly observed investigatory behavior in the predators, and some hunting cues were also observed.

Infrastructure associated with wind energy facilities can influence the behavior of animal predators and their prey, according to a recent study by University of California – Davis and the USGS.

Motion-sensor cameras were placed facing the entrances of 46 active desert tortoise burrows in a wind energy facility near Palm Springs, California. Recordings showed that visits to burrows from four predators increased closer to dirt roads, and decreased closer to wind turbines.